Chapter 10 Genetics-Mendel and Beyond - 10 Genetics Mendel...

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1 0 Genetics: Mendel and Beyond
10Genetics: Mendel and Beyond The Foundations of Genetics Mendels Experiments and the Laws of Inheritance Alleles and Their Interactions Gene Interactions Genes and Chromosomes Sex Determination and Sex-Linked Inheritance Non-Nuclear Inheritance
10The Foundations of Genetics Five thousand years ago or earlier, people were using applied genetics in the form of plant and animal breeding. The foundation for the science of genetics was laid in 1866, when Gregor Mendel used varieties of peas to conduct experiments on inheritance. Mendels research was ignored until the turn of the twentieth century.
10The Foundations of Genetics Plants have some desirable characteristics for genetic studies:
Figure 10.1 A Controlled Cross between Two Plants
10The Foundations of Genetics Josef Gottlieb Kölreuter made a few observations that Mendel later found useful. His study of reciprocal crosseshelped prove that both male and female parents contribute equally to the characteristics inherited by offspring. Before the acceptance of Mendels research, the concept of blendingwas favored. It was thought, for example, that the purple flowers resulting from red and blue parents could not be separated.
10The Foundations of Genetics Gregor Mendel worked out the basic principles of inheritance in plants in the mid-1800s but his theory was generally ignored until the 1900s. After meiosis had been described, several researchers realized that chromosomes and meiosis provided an explanation for Mendels theory.
10Mendels Experiments and the Laws of Inheritance Mendel selected varieties of peas that could be studied for their heritable characters and traits.Mendel looked for characters that had well-defined alternative traits and that were true- breeding, or that occur through many generations of breeding individuals. Mendel developed true-breeding strains to be used as the parental generation, designated P.
10Mendels Experiments and the Laws of Inheritance The progeny from the cross of the P parents are called the first filial generation, designated F1. When F1 individuals are crossed to each other or self-fertilized, their progeny are designated F2. Mendels well-organized plan allowed him to observe and record the traits of each generation in sufficient quantity to explain the relative proportions of the kinds of progeny.
10Mendels Experiments and the Laws of Inheritance Mendels experiment 1: A monohybrid crossinvolves one character (seed shape) and different traits (spherical or wrinkled).

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